The present invention relates generally to a signal waveform display system such as an oscilloscope, for displaying waveforms of input signals, and more particularly to a signal waveform display system which can laterally display signal waveforms on two different time scales side by side on the same screen.
In a conventional oscilloscope, when a display mode is set to a delay sweep mode, a portion of an entire signal waveform displayed on a screen is enlarged in the time axis direction. Either of the entire waveform or the enlarged partial waveform is selectively displayed on the screen, or the two different waveforms of the same signal are displayed simultaneously on two vertically split screen areas, as illustrated in FIG. 1.
Also, when a plurality of different signal waveforms are to be displayed, a plurality of oscilloscopes are provided to display the respective signal waveforms.
While the prior oscilloscope as mentioned above can employ the delay sweep mode to split the screen into two upper and lower areas for simultaneously displaying waveforms of a single signal on two different time axis scales, the delay sweep mode requires a high speed sweep for displaying temporally small portions of a signal in an enlarged view. However, a shorter sweep time period due to the high speed sweep results in a waveform displayed on the screen (for example, the waveform displayed on the lower screen area in FIG. 1) with a lower luminance.
Another problem with the prior art oscilloscope which may arise when two waveforms displayed on a single screen have large amplitudes, will overlap with each other to cause difficulties in viewing the two displayed waveforms. Although two waveforms may be controlled to selectively display them to prevent their displayed waveforms from overlapping, an operator is required to memorize a displayed signal waveform before a switching operation. If the operator cannot properly remember the waveform state before the switching operation was effected, the display must again be switched to the previous display state for confirmation. Thus, the alternate display involves complicated operations as well as requiring an operator to exactly memorize switched waveforms.
Further, when waveforms of a plurality of different signals should be compared with each other, they are displayed respectively on different oscilloscopes, the comparison of the waveforms is quite difficult to achieve because a waveform displayed on an oscilloscope must be compared with another waveform on another oscilloscope.